Main Traits of Realism
Realism is the belief that entities of a certain type have an objective reality, a reality that is completely ontologically independent of our conceptual schemes, linguistic practices, beliefs, etc. Thus, entities have an existence independent of the act of perception and of their names.
The doctrine had its beginnings with Pre-Socratic philosophers like Thales, Heraclites and Parmenides, but its definitive formulation was that of Plato and his theory of Forms. Later philosophers (especially Christians) amended and adapted the doctrine to suit their needs:
St. Augustine modified Plato's realism by holding that universals existed before the material universe in God's creative mind, and that humanity as a universal preceded individual men.
St. Anselm believed that he could derive truth about what actually exists from consideration of an ideal or universal, and argued that because God is the greatest of beings, he must exist in reality as well as in thought.
St. Thomas Aquinas (built on Aristotle’s Realism) argued that human reason could not totally grasp God's being, but that one could use reason in theology whenever it was concerned with the connection between universals and individual objects.
Realists tend to believe every new observation brings us closer to understanding reality. In its Kantian sense, realism is contrasted with idealism (the position that the mind is all that exists, and the external world is an illusion created by the mind). In a contemporary sense, realism is contrasted with anti-realism (any position denying the objective reality of entities) and with Nominalism (the position that abstract concepts, general terms or universals have no independent existence, but exist only as names). There are many different types of realism: representative realism, modal realism, moral realism, transcendental realism, organic realism, indirect realism, new realism, political realism, Christian realism, critical realism, etc.
There are two general aspects to realism. First, there is a claim about existence. Tables, rocks, the moon, and so on, all exist. The second aspect of realism concerns independence. The fact that the moon exists and is spherical is independent of anything anyone happens to say or think about the matter.
In medieval philosophy realism represented a position taken on the problem of universals. There were two schools of realism. Extreme realism, represented by William of Champeaux, held that universals exist independently of both the human mind and particular things — a theory closely associated with that of Plato. Some other philosophers rejected this view for what can be termed moderate realism, which held that universals exist only in the mind of God, as patterns by which he creates particular things. St. Thomas Aquinas and John of Salisbury were proponents of moderate realism. The second school – epistemological realism – represents the theory that particular things exist independently of our perception. Most contemporary British and American philosophy tends toward realism. Prominent modern realists have included Bertrand Russell, G.E. Moore, and C.D. Broad.